A Paleomagnetic, Geochemical and U-Pb Geochronological Comparison of the Thule (Greenland) and Devon Island (Canada) Dyke Swarms and Its Relevance to the Nares Strait Problem
Bibliographic record
Abstract
The Nares Strait controversy concerns the debate about whether or not a major sinistral transcurrent fault (the Wegener Fault) separates northern Greenland and Canada.To date no firm evidence has been found for the proposed 200 km sinistral offset, and to the contrary, geological correlations, mainly involving Paleozoic rocks across the Nares Strait, suggest that total left-lateral motion is no more than 70 km.The E-W trending Thule (Greenland) and Devon Island (Canada) dyke swarms lie on opposite sides of Baffin Bay and are offset sinistrally about 200 km, suggesting that if their correlation is established a convincing case for the Wegener Fault can be made.Paleomagnetic, geochemical and petrographic data allow, but do not yet establish, the correlation.Paleomagnetic results for Canadian sites (VGP = 6.9°N, 181.8 °E, A 95 = 12.7°, N = 5) and Greenland sites (VGP = 11.5 °N, 178.3 °E, A 95 = 13.8°,N = 4) are not significantly different at the 95 % confidence level.These levels are too large to resolve whether or not the Thule and Devon Island swarms have been offset.Geochemical data reveal a distinct and identical pattern in incompatible elements, while petrographically, the dykes are indistinguishable.U-Pb geochronological results for a Canadian dyke (720.2 ±2.0 Ma) and a Thule dyke (720.4 ±2.7 Ma) are identical within error and clearly identify the two sets of dykes as being parts of the same magmatic episode.Zusammenfassung: Bei der Nares Strait-Kontroverse geht es um die Debatte, ob eine bedeutende Links-Seitenverschiebung (die Wegener-Störung) Nordgrönland von Kanada trennt.Bis heute sind keine zwingenden Belege für die postulierten 200 km Transportweite gefunden worden.Im Gegenteil: Geologische Korrelationen von paläozoischen Gesteinseinheiten auf beiden Seiten der Meeresstraße reduzieren die maximalen sinistralen Transportweiten zu nicht mehr als 70 km.Die E-W-streichenden Thule-Gangschwärme (in Grönland) und Devon-Gangschwärme (in Kanada) liegen auf beiden Seiten der Baffin Bay und erscheinen ca.200 km sinistral versetzt.Falls die Korrelation dieser Gangschwärme gelingt, kann ein wichtiges Argument für die Existenz der Wegener-Störung geliefert werden.Paläomagnetische, geochemische und petrographische Daten erlauben eine Korrelation, wenn sie sie auch bisher noch nicht beweisen.Paläomagnetische Ergebnisse von kanadischen Gängen (VGP = 6,9°N, 181,8 °E, A 95 = 12,7°, N = 5) und Vorkommen in Grönland (VGP= 11,5 °N, 178,3 °E, A 95 = 13,8°, N = 4) sind im 95 % Konfidenzrahmen nicht hinreichend verschieden.Diese Daten sind jedoch nicht genau genug, um zu entscheiden, ob die Thule-und Devon-Gangschwärme versetzt sind.Geochemische Daten zeigen eine deutliche, identische Verteilung der inkompatiblen Elemente, während petrographische Daten gleichfalls keine Unterschiede zeigen.Geochronologische (U-Pb) Ergebnisse für einen kanadischen Gang sind innerhalb der Fehlergrenzen mit 720,2 ±2,0 Ma identisch mit 720,4 ±2,7 Ma für einen Thule-Gang.Die Ergebnisse machen deutlich, dass die beiden Gangprovinzen Teil desselben magmatischen Ereignisses sind.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".